Patterning carbon nanotube coatings by selective chemical modification

Abstract

This invention is directed to a method of patterning carbon nanotubes transparent electrically conductive coating/films, by modification of the applied carbon nanotube (CNT) network through use of sidewall group functionalization to disrupt electrical conductivity of the nanotubes. The resulting areas which undergo chemical modification are rendered more or less conductive than those areas which where not altered. This results in a patterned film, wherein said pattern is shaped to form electrodes, pixels, wires, antenna or other electrical component. In addition, the areas of chemically modified CNT can be returned to their original conductive state (i.e. reversible and repeatable), or fixed to yield a permanent pattern.

1 . A method of patterning an electrically conductive coating of a surface comprising: 
 applying carbon nanotubes to said surface to form a coating;    exposing areas of said coating to a reagent that modifies electrical conductivity of only said areas by functionalizing carbon nanotube sidewall groups.    
     
     
         2 . The method of  claim 1 , wherein applying comprises spraying, roll coating, vacuum deposition, and combinations thereof.  
     
     
         3 . The method of  claim 1 , wherein the carbon nanotubes are conductive, semi-conductive or a combination of both.  
     
     
         4 . The method of  claim 1 , wherein the carbon nanotubes are selected from the group consisting of single-wall, double-wall, multi-wall and combinations thereof.  
     
     
         5 . The method of  claim 1 , wherein the reagent comprises ultraviolet light at an intensity sufficient to functionalize the carbon nanotube sidewall groups.  
     
     
         6 . The method of  claim 5 , wherein the reagent further comprises a photoreactive chemical.  
     
     
         7 . The method of  claim 6 , wherein the photoreactive chemical is osmium tetraoxide in the presence of oxygen.  
     
     
         8 . The method of  claim 1 , wherein the carbon nanotube sidewall groups are functionalized by cycloaddition.  
     
     
         9 . The method of  claim 8 , wherein the cycloaddition is of an osmyl ester or a quinine-type functionality.  
     
     
         10 . The method of  claim 1 , wherein the modification reduces electrical conductivity along said areas.  
     
     
         11 . The method of  claim 1 , wherein the modification increases electrical conductivity along said areas.  
     
     
         12 . The method of  claim 1 , wherein the patterned electrically conductive coating forms an electrical circuit.  
     
     
         13 . The method of  claim 1 , wherein the patterning is reversible.  
     
     
         14 . The method of  claim 13 , wherein reversing the patterning comprises exposing said coating to UV light in the presence of oxygen and the absence of the reagent.  
     
     
         15 . The method of  claim 1 , wherein the patterning is fixed by exposing the coating to water.  
     
     
         16 . A patterned electrically conductive coating made by the method of  claim 1 .  
     
     
         17 . A method of selectively pattering a carbon nanotube coating comprising: 
 exposing the coating to ultraviolet light and a chemical reagent that functionalizes carbon nanotube sidewall groups.    
     
     
         18 . The method of  claim 17 , wherein the chemical reagent comprises osmium tetroxide and oxygen.  
     
     
         19 . The method of  claim 18 , wherein the oxygen comprises oxygen dissolved in a solvent.  
     
     
         20 . The method of  claim 17 , further comprising permanently fixing the patterning by exposing the coating to water vapor.  
     
     
         21 . The method of  claim 17 , further comprising removing the patterning by exposing said coating to oxygen and UV light.  
     
     
         22 . The method of  claim 17 , further comprising over-coating said carbon nanotube coating with a patterned conductor comprising applying a polymeric or inorganic binder to provide environmental protection to the conductive layer.  
     
     
         23 . The method of  claim 17 , wherein the chemical reagent comprises a diazonium reagent.  
     
     
         24 . The method of  claim 23 , wherein the diazonium reagent is selected from the group consisting of 4-bromobenzenediazonium tetrafluoroborate, 4-chlorobenzenediazonium tetrafluoroborate, 4-fluorobenzenediazonium tetrafluoroborate, 4-tert-butylbenzenediazonium tetrafluoroborate, 4-nitrobenzenediazonium tetrafluoroborate, 4-methoxycarbonylbenzenediazonium tetrafluoroborate, 4-tetradecylbenzenediazonium tetrafluoroborate, and combinations thereof.  
     
     
         25 . The method of  claim 17 , wherein the chemical reagent selectively functionalizes carbon nanotube sidewall groups to form patterns.  
     
     
         26 . A patterned carbon nanotube coating made by the method of  claim 17 .  
     
     
         27 . The coating of  claim 26 , which is applied to a transparent, conductive layer for storage of information.  
     
     
         28 . The coating of  claim 26 , wherein the information comprises personal information of one or more persons, professional information, company information, recreational information, dictionary information, business records or combinations thereof.